If there was a major emp blast knocking out all electronic and we managed to rebuild, would what was on the internet before the blast remain?

(Serious) Yes and No. Most data centers, substations and electric plants have EMP Protection. They're designed to take a direct lightning strike and remain operational. An EMP would be less than a lightning strike. The facilities would be tripped offline momentarily or to secondary power. Then turn back on. However everyone's home and electronics would likely be fried as would some transformers and power distribution units in neighborhoods. Servers outside of a first class datacenter would also be fried. And there'd likely be no computers to access the internet. (/Serious) The porn will still exist on someone else's computer. Just not yours and you can't see it. You'll have to do what people did in the 1800s. Whip out the family album for your yank session.